Solar-Plus-Batteries Could Supply Most Electricity

June 5, 2015

Rocky Mountain Institute (RMI) and HOMER Energy released a report in April 2015, The Economics of Load Defection, detailing where and when grid-connected solar-plus-battery systems could supply most of electricity needs that have traditionally come from the grid.

As retail prices for grid electricity climb and costs for solar photovoltaics (PV) and batteries continue their decline, grid-connected solar-plus-battery systems present an increasingly cost-effective option for customers in the next 10 to 15 years in many geographies. The report, which was completed using the HOMER® software, explains just how much electric load and revenue loss utilities could face, including implications for utilities and regulators and possible paths forward.

Compared to the off-grid solar-plus-battery systems modeled in RMI’s 2014 report The Economics of Grid Defection, the grid-connected systems modeled in this report are smaller and thus cost less, making them economic sooner for more customers in more places. As customers adopt the economically optimal configuration of these systems over time, the grid’s contribution to meeting customers’ electric loads shrinks significantly, while solar PV meets these loads for far lower costs.